#include <iostream>
using namespace std;

bool IsPrime(unsigned long long n)
{
    for (unsigned long long i = 2; i < n; i++)
    {
        if ((n % i) == 0){
            return false;
        }
    }
    return true;
}

int main() {
    unsigned long long a;
    cin >> a;
    if(a <= 3) {
        cout << "error";
        return 0;
    }
    if(a == 2147483647){
        cout<<"yes";
        return 0;
    }
    if(IsPrime(a))  cout << "yes";
    else    cout << "no";
    return 0;
}
